1. Field of the Invention
The present invention relates generally to electronic communications systems and methods, and particularly to an orthogonal frequency division multiple access (OFDMA) power allocation method.
2. Description of the Related Art
Radio resource management (RRM) procedures for Orthogonal Frequency Division Multiple Access (OFDMA) systems have to consider two main resources in the network: the frequency band and the power. The frequency band is typically divided into a number of sub-channels that must be distributed amongst users. Typically, in OFDMA, multiple user transmitters are transmitted simultaneously on different frequencies in the same time slot to make maximum use of the allocated bandwith. The different frequencies are referred to as sub-carriers. Sub-carriers may be grouped together to form sub-channels. The sub-carriers in a given sub-channel may be adjacent frequencies, or may be grouped together using other criteria. Scalable OFDMA is the OFDMA mode that is used in Wi-MAX. Scalability is achieved by adjusting the FFT size while fixing the sub-carrier frequency spacing at 10.94 kHz.
The RRM must also assign a specific amount of transmit power for each of the allocated sub-channels so that the sum of all power allocations does not exceed the total available power budget for the system. The process of allocating the sub-channels and power assignments is referred to in the literature as the sub-channel (or sub-carrier) power allocation problem for OFDMA systems. The RRM procedure performing this allocation problem plays a central role in the performance of the network. Modern wireless air interface technologies, such mobile WiMAX and Long-Term Evolution (LTE), depend heavily on such procedures to provide their high-speed data services.
Thus, an OFDMA power allocation method solving the aforementioned problems is desired.